In many technical fields the visible light spectrum is used to color code images in order to provide for a quick visual analysis, for example, of elevation, stress, strain, or temperature variation over an object or objects captured in the image. The spectrum of colors, as a qualitative scale of values, is calibrated to a quantitative scale of values, such that each color corresponds to a particular numeric value, or range of numeric values, within the overall range of the scale. A legend for interpreting such an image, typically including a color bar having the spectrum of colors aligned along the scale of quantitative values, is often overlaid on the coded image. In some cases, shades of gray or assorted patterns or textures may be substituted for the spectrum of colors as a qualitative scale of values.
In certain instances, an analyst of these coded images will want to focus their attention to particular areas of the image where quantitative values associated with the image (either measured or calculated) are within a targeted range. To facilitate this more focused analysis, either the overall range of the scale for coding the image may be decreased from that originally established, or portions of the originally established range may be ‘turned off’, that is, the colors (or shades of gray) associated with the portions of the range that are not of interest are removed from the image. A resulting image will have at least two portions: a first that is coded, and a second that is un-coded and merely presents a visible outline or structure of the captured object(s), which may, or may not, be absent of any color; such an image is referred to herein as a composite image. Manipulating the range, as such, is enabled by state-of-the-art computer software programs, and may be performed while the analyst views the image on a computer monitor or screen.
Turning off particular portions of the overall range, rather than decreasing the overall range, provides more flexibility, for example, by allowing the analyst to pick a plurality of discrete non-adjacent portions of the range to remain coded on the image. In addition, maintaining the same overall range provides some uniformity in color coding over multiple analyses, wherein a different discrete range has been selected for each analysis. One example of a type of analysis that uses composite images is a temperature profile analysis of an object or scene captured by an infrared camera. One example of an infrared camera system having the capability to display and capture composite images for analysis is the IR FLEXCAM® system including SmartView® software, available from Infrared Solutions, Inc.—a Fluke Company. This system creates a composite image of an object or scene in which infrared scale colors, i.e. colors arranged according to the visible light spectrum and calibrated to a selected temperature scale using radiometric techniques, are superimposed over visible light colors; the system further provides a “color alarm mode” that allows a user of the system to select one or more temperature ranges of interest so that only the visible light portion of the object or scene is displayed for those parts of the image that are not within the selected ranges. This color alarm mode is described in co-pending and commonly-assigned U.S. patent application Ser. No. 11/294,752, entitled, VISIBLE LIGHT AND COMBINED IMAGE CAMERA WITH A LASER POINTER, which is hereby incorporated by reference, in its entirety.
When viewing a composite image, for example, wherein one or more discrete ranges of values, within an overall range of values, have been selected for coding, it may be difficult to quickly determine exactly what ranges have been selected. Thus, there is a need for a type of legend that can facilitate intuitive interpretation of composite images.
Due to the limitations imposed on patent application drawings with respect to color, and for the purpose of clarity in reproduction, a qualitative scale of values used in FIGS. 1A-5 and 6C employs various patterns rather than the more typical colors of the spectrum of visible light. It should be noted that the scope of the present invention is not limited to any particular type of scale of qualitative values, nor to a particular resolution thereof.